1. Field of Invention
The present invention relates to a power supply circuit for operation light bulbs and, in particular, to a protection circuit that can prevent sparkles produced when replacing operation light bulbs from happening.
2. Related Art
Operation light bulbs are indispensable illumination devices in the medical system. They are elements easily been worn out but have to be looked after so as to make sure those in the operation rooms are useable. In practice, an operation light bulb usually contains a main light bulb and a spare light bulb to avoid the situation that the main light bulb goes off during an operation and prevents the continuation of the operation. The power supply circuit of the light bulb detects the operation of the main light bulb through a sensor unit and automatically switches the power to the spare light bulb or notifies a user to do the switching, thus maintaining the normal operation of the medical operation.
However, when replacing the operation light bulbs, there is still a current through the contact terminals of the operation light bulbs unless the power is turned off. Since the operation light bulbs normally have a power between 150W to 250W, the actual current through the contact terminals is at least 6A to 10A. The possible sparkles occurring at the contact terminals during the replacement of the operation light bulbs may result in oxidization of the contact terminals, thus lowering the conduction rate of the contact terminals, or even induce explosion in the operation room, risking the patients and the medical crew. Therefore, it is a highly concerned subject to provide a protection circuit that can prevent sparkles produced while replacing the operation light bulbs.
It is a primary object of the invention to provide a protection circuit to avoid sparkles produced when replacing operation light bulbs so as to elongate the lifetime: of the contact terminals of operation light bulbs. The circuit includes a control circuit and a sensor circuit. The control circuit is mainly composed of a microprocessor having the functions of providing a user operation interface, indicating the system""s state, generating a driving signal and processing signal detection. The sensor circuit uses different circuits according to different driving methods to achieve necessary controls. The sensor circuit can use such methods as pulse edge detection, voltage drop, or current detection.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.